Optimization of the Operating Voltage of Cobalt-Free Nickel-in-Medium Cathodes for High-Performance Lithium-Ion Batteries

Medium-nickel cobalt-free cathode materials have attracted much attention in recent years for their low cost and high energy density. However, the structural stability of nickel-based cathode materials becomes compromised when accompanied by the increasing of voltage, leading to poor cycling performance and, thus, hindering their widespread industrial application. In this work, we investigated the optimal charge cut-off voltage for the nickel-based cathode material LiNi_0.6Mn_0.4O₂ (NM64). Within the voltage range of 3.0 to 4.5 V, the electrode energy density reached 784.08 Wh/kg, with an initial Coulombic efficiency of 84.49%. The reversible specific capacity at 0.1 C reached 197.84 mAh/g, and it still maintained a high reversible specific capacity of nearly 150 mAh/g, with a capacity retention rate of 86% after 150 cycles at 1 C. Furthermore, NM64 exhibited an intact morphological structure without noticeable cracking after 150 cycles, indicating excellent structural stability. This study emphasizes the relationship between the stability of NM64 cathodes and different operating voltage ranges, thereby promoting the development of high-voltage layered nickel-based cathode materials.